Composite multifilament yarn

ABSTRACT

A MULTIFILAMENT YARN COMPRISING A PLURALITY OF FILAMENTS COMPOSED OF TWO KINDS OF THERMOPLASTIC HIGH POLYMERS HAVING DIFFERENT VISCOSITIES AND ARRANGED IN AN ECCENTRIC DISPOSITION IN THE CROSS SECTION OF EACH FILAMENT. MATERIAL HIGH-POLYMERS SHOULD PREFERABLY BE CHOSEN FROM POLYESTER GROUPS AND THE DIFFERENCE IN VISCOSITIES THEREOF SHOULD BE LARGE THAN 0.05. A FABRIC CONTAINING THE YARNS CAN BE PROVIDED WITH ENHANCED BULKINESS TOGETHER WITH UNIQUE HANDLING QUALITY.

United States Patent 3,570,235 COMPOSITE MULTIFILAMENT YARN Mototada Fukuhara, Akira Ueno, Isao Nihei, and Chikara Sano, Mishirna-slii, Japan, assiguors to Toray Industries, Inc., Tokyo, Japan No Drawing. Filed Oct. 15, 1968, Ser. No. 767,813 Claims priority, application Japan, Oct. 18, 1967,

Int. Cl. D02g 1/18, 3/24 US. Cl. 57-140 3 Claims ABSTRACT OF THE DISCLOSURE A multifilament yarn comprising a plurality of filaments composed of two kinds of thermoplastic high polymers having different viscosities and arranged in an eccentric disposition in the cross section of each filament. Material high-polymers should preferably be chosen from polyester groups and the difference in viscosities thereof should be larger than 0.05.

A fabric containing the yarns can be provided with enhanced bulkiness together with unique handling quality.

The present invention relates to an improved multi filament yarn, more particularly relates to an improved polyester multifilament yarn preferably used as filling yarns of a fabric so as to provide the fabric with enhanced bulkiness together with unique handling quality.

It is well-known that numerous coiled crirnps can be developed on a filament yarn by composite spinning of filaments from more than two different kinds of material polymers having different thermal shrinking properties in the form of an eccentric arrangement in the cross section of the filament, drawing the filament yarn and subjecting the filament yarn to a thermal treatment in a substantially relaxed condition.

The so-called composite filament yarns thus obtained are preferably used in manufacturing various textile prodnets on account of their unique characteristic features. Some of the examples of such utilization of the conventional composite filament yarns are found in the field of bulky knitted fabrics or crepe fabrics.

After repeated research work on the utilization of polyester composite multifilament yarns, the inventors of the present invention have succeeded in obtaining a novel polyester multifilament yarn which can provide a remarkably unique handling quality to a fabric containing the same.

The term a fabric of a remarkably unique handling quality hereinafter used refers to a fabric having improved bulkiness, moderate extensibility and enhanced flexibility when compared with the conventional fabrics made of synthetic filament yarns.

The conventional fabrics of this type have been obtained by utilizing bulky textured yarns mainly manufactured by the false-twisting method as the material weaving yarns, and for this reason, such fabrics have generally been called textured fabrics.

However, utilization of such conventional textured yarns in the manufacture of the textured fabric is neces sarily accompanied with several drawbacks.

Firstly, utilization of the false-twisted textured yarn requires doubling and twisting of two single yarns of different false-twisting directions in order to eliminate residual torque of the yarn due to twists imparted to the yarn. Unless this is done, the residual torque possessed by the yarn tends to develop so-called snarls on the yarn when the yarn is placed in a relatively relaxed condition during the following weaving operation. Such snarls obstruct smooth passage of the yarn through the eye of a wire heald or slits of a reed and this causes breakage of the yarn during operation or formation of weaving defects upon the fabric to be manufactured. Reduction in weaving efficiency and lowering of the fabric quality results.

Secondly, during false-twisting operation, individual filaments in the bundle of filaments are tightly pressed against each other to cause deformation of the cross sectional profiles thereof.

In other Words, cross sections of the individual filaments deviate substantially from the circular to polygonal ones. Thus the light reflection effect of the yarn bundle of filaments having such deformed cross sections, is lowered and this results in lowered luminous effect of the fabric manufactured from such filament yarns.

Thirdly, as is well-known, the false-twisting method usually employs a heat-setting operation using a heated plate or a heated cylinder. However, in case polyester filaments are subjected to such a heat-setting operation, lack of uniformity in the effect of the heat-setting operation tends directly to cause irregular affinity of the filaments obtained to dyestuffs. So, there is a great danger of uneven dyeing of the fabric manufactured of such conventional textured filament yarns.

Lastly, when such conventional textured multifilament yarns are used in weaving fabrics having relatively a larger number of intersections of warps and fillings in the construction thereof such as tropicals, the residual torque of the yarn due to twists previously imparted to the yarn during false-twisting operation is liable to de velop pebbles upon the fabric surface and the quality of the fabric becomes considerably lowered or completely different from that desired.

A principal object of the present invention is to provide an improved polyester multifilament yarn which can favourably be used for manufacturing high quality fabrics provided with appearance and handling quality resembling those of the conventional textured fabrics while eliminating drawbacks which are present in the conventional textured fabrics.

Another object of the present invention is to provide an improved polyester multifilament yarn which can be processed through weaving or knitting operation without causing troubles which are often observed in case the conventional textured filament yarns are processed.

A further object of the present invention is to provide an improved polyester multifilament yarn having uniform affinity to dyestuffs and assuring even dye effect upon the fabric containing the same.

As is well-known, a composite filament is provided with coiled crimps. The number of the clockwisely spiralling coils and that of the counterclockwisely spiralling coils are approximately equal along the longitudinal direction of a composite filament. So, the residual torques developed on the composite yarn will cancel each other,

and the composite filament as a whole will not be provided with such residual torque which is usually present in the conventional textured filaments. This is one of the outstanding features of the polyester multifilament yarn of the present invention. Furthermore, the manufacturing process of the filament yarn of the present invention does not include imparting a high degree of twists to the filament yarn while applying a heat-setting operation upon the filament yarn during the process and the absence of such operations, which often effect deformation of the cross sectional profile of the filament yarn to be processed, assures elimination of the cross sectional deformation of the filament yarns. This is another of the outstanding advantages of the present invention.

However, it was made apparent by the inventors of the present invention that not all of the polyester multifilament yarns but only the polyester multifilament yarn defined by the scope of the present invention can effectively and favourably provide the above-described advantages while eliminating drawbacks which the conventional textured filament yarns have.

In accordance with the foregoing discussion, the polyester multifilament yarn of the present invention is characterized by a composite filament wh ch is substantially composed of two or more polyester polymers having different thermal shrinking properties arranged in an eccentric disposition in the cross section of the filament, the percent apparent shrinkage of the filament yarn in boiling water ranges between 30 and 65%, percent true shrinkage of the filament yarn by dry heating is smaller than 10.0%, the value of the contraction stress measured at 180 C. is smaller than 120 rug/denier and the number of crimps developed upon the filament by treatment with boiling water is larger than 16 crimps/ cm.

In case the material polyester multifilament yarns are not provided with the above defined characteristic features, the fabric containing the same can not be provided with the advantages of the present invention. Paper-like handling of the fabric, development of pebbles upon the fabric, excessive contraction of the width of the fabric during finishing or dyeing operation of the fabric and rough handling of the product obtained will be observed.

An outline of the method employed for manufacturing the polyester multifilament yarn of the present invention will now be briefly introduced. Selection of the material polyester polymers should be done in such a manner that the intrinsic viscosities of the polymers should be different from each other. One of the component polymers should preferably have an intrinsic viscosity ranging from 0.45 to 0.55 and the other component polymer should preferably have an intrinsic viscosity ranging from 0.60 to 0.85. Both of the component polymers should be meltspun at a spinning temperature ranging between 290 and 300 C. in such a manner that these component polymers are arranged in an eccentric disposition, or more preferably in a bimetal-like disposition, in the cross section of a filament. After extrusion, the bundle of filaments is subjected to coagulation by a cooled air flow and taken up onto a package at a winding-up tension larger than 0.15 g./denier.- Next the multifilament yarn thus obtained is subjected to a drawing operation in a drawing machine provided with a heated pin and a heated plate. Drawing is carried out at a drawing ratio ranging between 3.0 and 3.8. The temperature of the heated plate should be maintained between room temperature and 180 C. and the temperature of the heated pin should be in a range between the glassy transition point temperature and 160 C. After the drawing operation, a relaxation thermal treatment should be applied upon the drawn multifilament yarn in an equipment provided with heated cylinder through which the multifilament yarn is passed. The temperature of the heated cylinder should be maintained between 130 and 240 C., more preferably between 200 and 230 C., and the relaxation ratio should range from to 70%, more preferably around 20%. Then the multi- 4 filament yarn thus obtained is provided with numerous fine spirally coiled crimps thereon developed.

As will be made clear in the following examples, provision of the polyester multifilament yarn of the present invention requires optimum combination of the abovedescribed processing conditions throughout the entire manufacturing processes. That is to say, a random selection of the processing conditions within the range abovedefined cannot assure preferable results upon the multifilament yarn obtained.

The above-described polyester polymers should preferably be chosen in combination from a group composed of terephthalic acid, lower alkyl derivatives of terephthalic acid, ethylene glycol, bis-2-hydroxyl-ethylterephthalate or its low polymers and polyesters containing at least 70% by weight of polyethylene terephthalate.

The combination of polymers chosen from the abovedescribed polyester group should be determined in such a manner that the difference in the intrinsic viscosities of polymers should be as hereinafter described. For example, a combination of terephthalic acid with ethylene glycol is preferably employed.

The above-described polymers can also contain copolymer components chosen from a group composed of aliphatic di-carboxylic acids such as oxalic acid, adipic acid and azelaic acid; aromatic di-carboxylic acids such as isophthalic acid, phthalic acid, 2,6-naphthalene di-carboxylic acid and diphenic acid; di-carboxylic acid having alicycles such as 1,2-cyclobutane di-carboxylic acid; dicarboxylic acid containing elements other than carbon, hydrogen and oxygen such as compounds having structures shown by the following general formulas COOH COOH COOH for instance S-sodium sulfophthalic acid and 5-rnethylsulfophthalic acid; multifunctional compounds such as trimellitic acid and pyromellitic acid; lower alkyl esters and glycol esters of such multifunctional compounds; polyoxy compounds such as di-ethylene-glycol, propylene glycol, polyethylene glycol, butendiol, tioglycol, p-xylylene glycol, 1,4-cyclohexan-di-methanol, 2,2-bis(p-2-oxyphenyl) propane, 2,2 bis(p-oxyethoxyphenyl) propane, g1ycerol and pentaerythritol; and p-oxyethoxy benzoic acid, p-oxymethyl benzoic acid and glycollic acid. It is also possible for the polymers to contain such pigments as carbon black, phthalocyamine, titanium pigments and silicic anhydride, and phospho-compounds such as phosphoric acid, phosphorous acid, tri-phenyl-phosphate, trimethyl-phosphate and tri-phenyl-phosphate. Furthermore, in case the viscosity of the molten polyester solution is remarkably low, it is also recommended that additives such as boric compounds or aluminate compounds be mixed.

The terms and values used in the explanation of the following examples are defined and measured in the manner hereinafter described.

The term intrinsic viscosity (1 refers to a viscosity of polyester polymer dissolved with o-chlorophenol solution measured at 25 C.

The drawing ratio of the filament is given by the ratio of the peripherical speed of the drawing roller with respect to the feed roller and the percent relaxation ratio of the filament is given by wherein:

V =The peripheral speed of the feed roller V =The peripheral speed of the relaxing roller The characteristic features of the multifilament yarn of the present invention are measured in the manner below described.

(1) NUMBER OF CRIMPS A crirnped filament of 20 cm. long is loaded with a weight of l mg./denier, and the number of crimps per unit length (1 cm.) observed on the filament is counted along cm. length of the filament.

(2) APPARENT PERCENT SHRINKAGE A skein of -10 winds is prepared on a yarn reeler having a circumferential length of 1 meter at a taking up tension lower than 50/mg./denier. By folding the skein, a bundle of yarns containing single yarns is obtained. The length (a) of the bundel of yarns under an initial loading of 1 mg./denier is recorded. Next, the bundle of yarns is immersed into a hot water bath maintained at 98 C. for 15 minutes in a relaxed condition. This is removed from the bath, water drops sticking to the bundle of yarns are eliminated by Wrapping the bundle of yarns with gauzes or filter papers. Again the bundle of yarns is loaded with a weight of 1 mg./denier and the length (b) of the bundle of yarns in a loaded condition is recorded. Then, the percent apparent shrinkage of the yarn is given by:

(3) PERCENT TRUE SHRINKAGE The speciment bundle of yarns is prepared in the same manner as in case of the percent apparent shrinkage, and the length (l of the bundle under a loading of 200 rug/denier is recorded. Next, the bundle is subjected to a dry thermal treatment held at 160 C. in a relaxed condition. After the treatment, the bundle is again loaded with a weight of 200 mg./denier and the length (l of the bundle is recorded in the loaded condition. Then, the percent true shrinkage of the yarn is given by;

P pa... Z

(4) CONTRACTION STRESS A crirnped yarn of cm. long is loaded with a weight of 1/30 g./denier and, in the loaded condition, im-

mersed into silicon oil bath maintained at 180 C. The stress created on the yarn is recorded using a strain meter.

The following examples are illustrative of the present invention but are not to be construed as limiting-the same.

EXAMPLE 1 Two material polyethyleneterephthalate polymers having intrinsic viscosities of 0.50 and 0.80, respectively, were prepared. By composite spinning the material polymers at a spinning temperature of 295 C. in the so-called bimetallike configuration, an undrawn multifilament yarn having a total fineness of 500 denier and containing 48 filaments was obtained and taken up onto a package at a winding-up tension of 0.20 g./denier. Next, the undrawn multifilament yarn was subjected to a drawing operation at a drawing ratio of 3.5 by passing through a drawing machine wherein the temperature of the heated pin was maintained at 98 C., the temperature of the heated plate was maintained at 150 C. After the drawing operation, the total fineness of the yarn was 150 denier. By applying a relaxation thermal treatment upon the drawn multifilament yarn, a multifilament yarn (Sample No. 1) provided with numerous fine crimps was obtained. The temperature of the heated cylinder used in the relaxation thermal treatment of pebbles upon the fabric surface was observed, resulting characteristic features of the yarn thus obtained are illustrated in Table 1 with Sample No. 1.

Further, a tropical fabric was manufactured using the multifilament yarns thus obtained for both the warps and fillings, and the fabric was subjected to the usual finishing process composed of relaxed scouring, squeezing and drying, heat-setting, scouring, dyeing, squeezing and drying and the final setting. The resulting characteristic features of the fabric thus obtained are also illustrated in Table 1 wherein it is apparent that no development of pebbles upon the fabric surface was observed, finishing contraction of the width of the fabric was adequate as this was 23% and the fabric was provided with suitable thickness together with good handling quality.

EXAMPLE 2 Nine types of polyester multifilament yarns of 150 denier (Samples No. 2 to 10) were manufactured using the method and equipment used in the preceding example. However, in the present example, processing conditions were selected as follows.

Intrinsic viscosity of the low viscosity component polyrner0.450.55.

Intrinsic viscosity of the high viscosity component polymer0.600.85.

Number of filaments contained in a single multifilament yarn24-72.

Temperature of the heated plate in the drawing proce'ss--Up to 180 C. or none.

Drawing ratio3.0-3.8.

Circumferential temperature during relaxation-- Relaxation ratio10-7 0% The resulting characteristic features of the multifilament yarns obtained are illustrated in Table 1. Further, using each of the multifilament yarns thus obtained, tropical fabrics were woven, finished and dyed in a manner similar to that in the preceding example, and the resulting properties of the fabric made from each are also shown in Table 1. As is apparent from the results shown in the table, fabrics made of the multifilament yarns whose properties are outside the range defined by the scope of the present invention are accompanied with development of pebbles, excessive contraction of the fabric width, paper-like handling due to lack in thickness, rough touch and insufiicient resilience.

EXAMPLE 3 A multifilament yarn of denier was manufactured from polyethyleneterephthalate polymer having an intrinsic viscosity of 0.48 and polyparaoxyethylenebenzoate polymer having an intrinsic viscosity of 0.56. This manufacture employed the equipment used in Example 1 and the processing conditions employed in Example 2. The multifilament yarn obtained (Sample No. 12) is provided with properties within the range defined by the scope of the present invention as shown in Table l, and the tropical fabric made of the yarn is also provided with excellent properties which can meet the commercial requirements. On the contrary, the fabric of Sample No. 11 was accompanied with development of pebbles and rough handling, the properties of which was outside the range defined by the scope of the present invention. 

